July 3, 2010


Figure 1: Axial unenhanced CT image of the brain shows an isodense mass in the left posterior fossa with minimal, if any, mass effect.
Figure 2: Axial contrast-enhanced T1W MR image shows a large homogeneously enhancing extra-axial mass (star) near the left petrous bone overlying the sigmoid venous sinus (arrow).

Facts: Meningioma
  • Tumors of meningeal cells (typically arising from meninges but can also be found in the choroid plexus, tela choroidea and arachnoid villi); therefore meningiomas can be seen in the meninges, spinal canal, intraventricular, and pineal regions
  • Common, greater than 20% of all primary intracranial neoplasms
  • Female:male = 3:2 to 2:1; mostly in late middle age
  • Pathology: benign, atypical and malignant
Imaging Features
  • Homogeneous, lobulated, well-circumscribed mass with uniform dense enhancement following contrast administration
  • Common locations: parasagittal > convexity > sphenoid ridge
  • High attenuation on unenhanced CT, iso- to mildly hypointense on T1W MR images
  • May calcify in up to 1/4 of all cases, best seen on CT. Calcifications can be microscopic, punctate, large, peripheral or central. Malignant meningiomas rarely calcify.
  • Hyperostosis can be seen in up to 1/2 of cases that meningiomas are immediately adjacent to the bone. Common in 'en plaque' meningioma
  • Uncommon to have bone destruction (if pure destruction think of metastasis, sarcoma or myeloma)
Our case: benign meningioma overlying the sigmoid sinus without invasion. It is important to note if the meningioma is adjacent vascular structures for optimal surgical planning.

1. Drevelegas A. Imaging of brain tumors with histological correlation, 2002.
2. DeAngelis LM, Gutin PH, Leibel SA. Intracranial tumors: diagnosis and treatment, 2002.

1 comment:

Unknown said...

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